I. Field of the Invention
This invention pertains to a hand-piece for an injection device or similar apparatus used to inject a therapeutic fluid into human or animal tissues, and more particularly to a hand-piece which includes a needle movable along a longitudinal axis, which needle is optionally rotating about said axis as well.
II. Description of the Prior Art
It is well documented in both dental and medical literature that pain, tissue damage and post-op complications have long been tolerated as negative side effects from the use of existing hypodermic drug delivery injection systems. The pain and tissue damage are as a direct result of uncontrolled flow rate in conjunction with excessive pressures created during the administration of drug solutions within the tissues. Subjective pain response of a patient has been demonstrated to be minimized at specific flow rates during the administration of a drug. Also, it has been scientifically demonstrated that particular pressures (excessive without occlusion, per se) for a specific tissue type will cause damage. It is therefore critical that a specific flow rate in conjunction with a specified pressure range be maintained during the delivery of fluids (drugs) when a subcutaneous injection is given preventing subjective pain response as well as tissue damage. It is also necessary that this system have the capability to aspirate under controlled conditions of rate and pressure to avoid the same negative side effects during fluid movement. U.S. Pat. No. 5,180,371 to Spinello, incorporated herein by reference, presented an invention which allowed a rate to be set for the drug via a hypodermic needle disposed in a hand-piece.
One of the goals of dentistry and medicine should be to administer care to patients in the most humane and painless manner. The sine qua non of any treatment is to produce a desired result without causing damage or pain to the individual. Therefore there is an important need in all fields of surgery for an injection system which can be used to administer a fluid while causing substantially no pain or tissue damage to the patient.
Another goal of dentistry and medicine in general is to insure that during any procedure involving interaction between a dentist or other care giver and a patient, utmost care is taken to protect the care giver from injury and/or infection with diseases.
The use of hollow-core needles is the standard in drug delivery in medicine and dentistry. The use of the hollow-core needle dates back over 150 years when Charles Pravaz, a French general surgeon, patented such a device. It has been recognized that the use of hypodermic needles, which activity is endemic in the field, is one particularly hazardous activity which could cause injury. More particularly, the use of a hypodermic needle in dentistry and other medical fields has been shown to put the operator at risk to inadvertent needle sticks presenting a potential high risk to infection disease transmission for health care workers.
Currently, there are several auto-retraction type syringes are known that provide increased safety by allowing the protruding needle to be retracted into a protective sheath after use. However, current syringes require the use of a palm-thumb grasp during their use. This type of hand dexterity presents a potential risk of inadvertent needle stick during entry and withdrawal from the patient tissues. Other syringes are provided with removable caps. However, this configuration does not solve the problem in a satisfactory manner.
All of these prior art references have either one or more of the following deficiencies.
1) The use of a hollow needle that is rigidly affixed to the end of a syringe-, tubing or hand-piece. The protruding needle presents a risk of inadvertent needle stick to the operator.
2) Existing auto-retracting syringes and the like require the operator to use a palm-thumb grasp to operate. This structure creates an increased risk of inadvertent needle stick to the operator.
3) Existing auto-retracting syringes and the like require the operator to make use of the hand to physically retract the needle, thereby, making it difficult and cumbersome to perform.
Some prior art syringes and needles with sheaths or caps are disclosed in the following U.S. Pat. Nos.: 5,120,310; 5,188,613; 5,267,961; 5,389,076; 5,423,758; 5,578,011; 5,632,733; 5,637,092; 5,810,775; 5,030,209; 4,911,693; 4,900,310; 4,813,426; 4,795,432; 4,664,654; 4,695,274; 4,966,592; 4,747,831; 4,900,311; 5,411,487; 5,106,379; 5,713,873.
With the rise of infectious diseases, i.e., hepatitis and AIDS, protection of the health care workers has become a needed priority because, as indicated in the medical/dental literature, inadvertent needle sticks represent a significant risk to our health care providers. In the past 15 years regulatory agencies such as OSHA have attempted to improve the use and safety of needles in the health care industry further accentuating the need for an effective means of preventing needle sticks.
In addition, various medical organizations have suggested and several states have instituted rules for the protection of care givers while providing injections to patients. More specifically, rules have been promulgated requiring that injection needles on syringes be provided which can be easily removed prior to an injection and re-installed immediately after an injection.
The proposed invention has been designed to eliminate the potential of inadvertent needle sticks during and after use.
Another related problem addressed by the present invention pertains to the deflection or bending of needles as they are inserted into the tissues of a patient. This deflection occurs because the needle is usually flexible because of its relatively small cross-sectional area and cannot resist effectively the axial and radial forces present during the insertion. The deflection is undesirable because it provides additional resistance during the insertion, to the movement of the needle and makes it difficult to guide the needle to a particular site. Moreover, if a needle is deflected, bent or otherwise deformed during insertion, it may cause more pain to the patient, trauma to the local tissues and other undesirable effect. It has been discovered (as disclosed in co-pending provisional application serial No. 60/173,374 filed Dec. 28, 1999), incorporated herein by reference, that these disadvantages are eliminated or at least alleviated if the needle is rotated about its longitudinal axis as it is advanced along the axis into the patient tissues. While rotating devices are known which rotate about their longitudinal axes to allow drilling through bony tissues, these devices do not allow high level tactile control during use. Other syringes do not allow the use of a bi-directional rotational insertion technique to be used during a power assisted injection process.
In view of the above-mentioned disadvantages of the prior art, an objective of the present invention is to provide an injection device having a needle which can be selectively advanced from a retracted position in which the needle is hidden, toward an open position in which a therapeutic agent can be administered effectively, and can be retracted back to the retracted position before disposal.
A further objective is an injection device adapted to provide injection to a selected site and/or tissue by using a selective bi-directional rotational movement of the needle to prevent deflection of the needle.
Yet another objective is to provide an injection device which allows an operator to advance a needle at a manually controlled rate and with a hand-piece which is held steadily in a relatively stationary position with respect to the patient.
A further objective is to provide an injection device which can be used repeatedly to advance and retract a needle in a linear, rotational or bi-directional rotational motion.
Other objectives and advantages of the invention shall become apparent from the following description.
Briefly, an automatic injection device constructed in accordance with this invention includes a source of fluid to be injected, a needle, handle with a housing and a coupling used to selectively advance the needle out of the hand-piece, preferably under the control of the operator, and once an injection is complete, to retract it back into the hand-piece. Advantageously, the needle may be protracted and retracted several times during multiple uses on the same patient. The device may be a drug delivery device which serves to inject medicament from a tank or reservoir. This includes but should not be limited to infusion type pumps, syringe pumps, such as the Wand(copyright) made by Milestone Scientific of Orange, N.J.
In one embodiment, of the invention, a spring is provided in the housing which is arranged to bias the needle. Preferably the needle is biased toward its retracted position so that if the needle is advanced to extend outwardly of the housing and then released, it automatically returns to the retrieved position within the housing thereby reducing the likelihood that the needle pricks or otherwise injures an operator, the patient, or anyone else. Locking members are also provided which are used to secure the needle in the firstxe2x80x94that isxe2x80x94the retrieved position, or the second position. The coupling may be arranged and constructed to cooperate with the housing so that as the needle is advanced out of the housing, it is automatically and simultaneously rotated about its longitudinal axis. Typically, the needle may be rotated by about 45-270xc2x0. Preferably the needle is rotated by about 180xc2x0. This may be accomplished, for instance, by providing a helical groove on an inner surface of the housing and a boss on the coupling. As the coupling moves through the housing, its boss rides through the groove and this caming action causes the coupling, and the needle to rotate. If the groove is oriented in the same direction, the rotational motion is uni-directional. The groove can also be made to change direction one or more times along its length, in which case the needle undergoes a bi- or multi-directional motion. The term uni-directional is used to describe motion in the same sense, e.g., clockwise or counterclockwise. The term bi-directional is used to describe a motion that changes sense, e.g., initially clockwise, then counterclockwise.
Rotation may also be imparted to a needle affixed to a standard syringe. In this case, the needle is mounted to one wall of the barrel using a ball-bearing mounted, or other frictionless surface. A plunger is coupled to the other side of the barrel in a manner which forces the plunger to rotate as it is inserted into the barrel to force liquid from the barrel to be ejected through the needle. The plunger and the needle are coupled so that the rotation of the plunger is transmitted to the needle.